Circuit-controlling device



March 5, 1929. H. c; PARKER CIRCUIT CONTROLLING DEVICE Filed April 20, 1925 Patented Mar. 5, 1929.

UNITED STATES HENRY C. PARKER, 0F PHILADELPHIA,

PENNSYLVANIA, ASSIGNOR TO LEEDS &;

NOBTHRUP COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION 01' PENNSYLVANIA.

CIRCUIT-CONTROLLING DEVICE. v

\' Application filed April 20, 1925. Serial No. 24,591.

My invention relates to heat or temperature responsive devices for effecting any suitable control, and more particularly to that type of instrument known as a thermostat 0r thermo-regulator.

An instrument of this character comprises an expansion member of mercury or equivalent conducting fluid with which co-acts an electrical contact in such manner that the mercury upon expanding will close a circuit at a predetermined temperature. It has been customary heretofore to construct the contact of platinum. This metal, however, sooner or later will amalgamate with the mercury, and when this occurs the accuracy of regulation or control is seriously affected.

In accordance with my invention amalgamation or wetting, with consequent erratic or late action, is prevented and to this end, I provide a contact or terminal that will not unite, combine or alloy with or be wetted by the material constituting the expansible element. 1

Further in accordance with my invention, a heat or temperature responsive device and particularly a thermostat or thermo-regulater is so constructed that the temperature at which regulation will occur may readily be changed to any desired value.

For an illustration of some of the forms my invention may take, reference is to be had to the accompanying drawing, in which:

Figure 1 is a view, partly in section, of an instrument constructed in accordance with my invention. a i

Fig. 2 is a sectional view, illustrating a modification.

Fig. 8 is a sectional view illustrating a modification of the chamber in which the expansible fluid may be stored.

Referring to Fig. 1-, a represents a member formed of any suitable material, preferably glass. This member is so constructed as to provide enlarged spaces or bulbs 5 and 0 at any desired points, preferably near the ends of the member a. Connecting the bulbs b, c is a restricted, capillary-like passage (1,-

which is enlarged at anydesired points pref erably as shown at e, f and g. The diameter of the passage 01 connecting the enlarged spaces f and 9 should be decreased as shown at it so as to form a so-called clinical constriction. The member a is provided with a suitable scale 13 for a purpose hereinafter described,

Sealed into the wall of the member a at any desired points are the contact members or terminals j and 7a to which are connected the conductors Z and m in the circuit to be controlled. One or more additional contacts, n, may be sup lied to give a series of temperatures at which regulation will occur. The lower contact j may be sealed into the memher a at a point adjacent the enlargement 6. By so doing the sealing operation is facilitated; however, it is to be understood that the enlargement 6 may be omitted and the contact j sealed into the member a at any desired point along the longitudinal axis of the passage d. The contact k is likewise sealed into the member a at a point beyond or above the contact 7'. In order to attain maximum sensitivity the capillary passage d should not be enlarged at the point at which the contact is communicates therewith.

The composition of the material forming the lower contact 3' is immaterial. At the upper contacts is and n, however, the circuit is made and broken depending on the particular contact in use, and these upper con-- tacts'must be formed of a material which will not unite, combine or alloy with or be wetted by the mercury or equivalent material contained within the chamber 6 and expanding into the capillary passage 03. When mercury is used as the expansible material, this object may be attained by constructing contacts Z: and n of a metal or alloy which will notamalgamate with orbe wetted by the mercury. At the same time, this metal or alloy should have a coefficient of expansion corresponding to that of the material forming the chamber 7).

Tungsten and molybdenum, together with the metals in the eighth group of the periodic system with the exception of platinum oiier considerable resistance to amalgamation. The eighth group comprises besides platinum, iron, nickel, cobalt, ruthenium, rhodium, palladium, osmium, and iridium. In accordance with my invention any one of the metals noted above may be used as a contact either singly, or combined, or as an alloy with other metals either within or without the eighth group, and such alloy or combination may include either a large or a small proportion of the metals above noted. 7

The use of glass having a coefficient of expansion similar to that of one of the above noted metals or their alloys is also within the to the bulb b in any desired manner.- Thisaction causes passage of the expansiblematerial through the capillary passage d, and

beyond the clinical constriction h. When the source of heat is removed, the clinical con; striction prevents ready passage of the expansible material toward the bulb b, the result of the operation being that there is less material in the bulb. Hence, it requires a,

higher temperature to expand the material and cause the same to reach the contact A: or n. In order to lower the temperature at which regulation will occur, it is necessary to shake the device, whereupon some of the imprisoned material above the clinical constriction It will pass into the main reservoir. This causes accumulation of material in the bulb b, the result being that a lower temperature subsequently applied is sufficient to raise the expansible material until it reaches the contacts 76 or n.

The scale i in connection with the column of mercury above the clinical constriction h is arranged to provide a reading at which regulation will occur. Thus, when the top of the column above the constriction it reads 20,it is to be understood that regulation will occur when the temperature of the bulb Z) stands at that figure; in other words, when the scale reading is 20, the material from bulb b will just reach one of the upper contacts, thereby causing operation of the external control apparatus.

Figure 2 shows a simpler form of my invention and includes a member a formed of any suitable material, preferably glass. This member is constructed so as to provide enlarged spaces or bulbs b and c at any desired points, preferably near the ends of the member at. Connecting the bulbs 6 c is a restricted capillary-like passage (1 Sealed into the wall of the member a at any desired points are the contact members or terminals j and 70 to which are connected the conductors Z and m in the circuit to be con-' trolled. One or more additional contacts, 11 may be supplied to give a series of temperatures at which regulation will occur. passage (.13 is preferably, but not necessarily, enlarged at e in order to facilitate the sealin operation. As in Fig. 1, the contact at which the circuit makes and breaks, and shown in Fig. 2 at k or n must be made of a material that will, not .amalgamate, combine, unite, alloy, or be wetted by the mercury or equivalent material forming the expansible material.

The bulb 0 constitutes a storage chamber in which excess material may be stored after a setting has been made, thereby preventing an accidental change of setting should the bulb b slightly overheated. If desired, a bulb shaped as the goose neck 0 of Fig. 3 could lie substituted for the correspondingbulb of ig. 2. i

The word wetted? when used in the appended claims is used in the generic sense and Is to be understood as including any amalgamatmg, alloymg, comblmng, or like aetlon that may take place between the contact and the material, such as mercury, forming the expansible element.

What I claim is: 1. A circuit controlling device comprisin a member, forming a chamber, .mercury in said bhamber, and a co-acting electrical contactof an alloy of platinum and iridium.

2-. A temperature-responsive device comprising a member forming a chamber, mercury in said chamber, and a co acting electrical contact of material that is not wetted by mercury sealed into a wall of said chamber.

I 3. A temperature-responsive device comprising a member forming a chamber, mercury-in said chamber, and aco-acting electrical contact of material that is not wetted by mercury sealed into a wall of said chamber and having a coefiicient of expan sion substantiallythe same as said member.

4. A temperature responsive device comprising a closed tube-like member provided with bulbs adjacent its ends with a restricted passage connecting said bulbs, one of said bulbs being shaped as a goose neck and an electrical contact sealed into the wall of said member.

HENRY C. PARKER. 

